Professor Pedro M. Gadea taught at the Universities of Santiago de Compostela and Valladolid, Spain. He is now a scientific researcher at the Instituto de Fìsica Fundamental, CSIC, Madrid, Spain. He has published more than sixty research papers on several topics of differential geometry, algebraic topology and automatic speech recognition. He has also been advisor of four PhD theses. His current interests are in differential geometry, and specifically in Riemannian, Kähler, quaternion-Kähler and Spin(9) manifolds and structures, and their applications to supergravity. Outside of mathematics, his chief interests are history and minerals.
Professor J Muñoz Masqué taught at the University of Salamanca, Spain. He is currently a scientific researcher at the Instituto de Seguridad de la Información (ISI), CSIC, Madrid, Spain. He has written more than one hundred research articles on calculus of variations, Riemannian geometry, differential invariants, gauge theories, and public key cryptography, and he is
